Automatic Telephone Recorder

March 2, 2010 by Mike Szczys 40 Comments

[James Bond] types and those suffering from a hefty dose of paranoia can now record all telephone conversations. [Trax] built this module that monitors the phone line and starts recording when a handset is picked up. A computer does the actual recording, triggered by the microcontroller via a USB connection.

We like the use of an old PCB for a faceplate, we’ve certainly got some duds of our own sitting around. The three cords are a bit confusing though. One for the phone line, one for the USB, but what does the third do? Is it an audio-out connection?

We’ve asked [Trax] to post a schematic and source code if possible so that might clear up the mystery.

Update: [Trax] let us know that there is a red button with white lettering at the bottom labeled “download”. This contains schematic, code, pcb layout, and PC software. We just missed it the first time around.

DoomBox: Classic Keys Meet Tiny Screen

March 1, 2010 by Mike Szczys 24 Comments

The doomBox is a dedicated gaming rig for lovers of ID Software’s classic title. [JJ] built this from an old Kodak DC290 camera that had a broken lens. Since this runs the Digita OS, he was able to use the Doom port that already exists. But the camera’s factory buttons were not well suited as controls. By whipping up his own button board, and using the traditional keyboard keys for the button caps, he achieved a much more comfortable (yet squint-inducing) gaming experience. The finished project resides in an all-too-familiar black project box. See him fire it up after the break.

The original Doom for Digita OS pages seem to be down so here’s an alternate if you’re interested.

Update: Looks like the original website is back up.

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Two Input Devices Made With Common Items

February 27, 2010 by Mike Szczys 19 Comments

Here’s two input devices you can easily build with materials you already have on hand.

To the left, [John] built a 3×3 keypad matrix from paper and tinfoil. The rows and columns are made up of strips of tin foil on the front and back layers of paper. The layers are separated by spongy double-stick tape. A ‘keypress’ results when the gap between the conductors is compressed with your finger.

In much the same way, [Dave Fletcher] built a touch potentiometer. He made two resistance plates by scribbling pencil lead on sheets of paper. When the two plates face each other, separated by the same type of foam tape as before, they can be pressed together to form a circuit with a variable resistance. This results in a crude version of the SparkFun softpot.

Oscilloscope Doubles As A Serial Terminal

February 24, 2010 by Phil Burgess 25 Comments

PC-based USB oscilloscopes are fast becoming all the rage. [Matt Sarnoff’s] Terminalscope takes the reverse approach, adapting an oscilloscope into a full serial terminal. You may have seen something similar before in the Dutchtronix/SparkFun O-Clock, but [Matt’s] project goes one further by adding a PS/2 keyboard port for full bidirectional serial communication, and with much sharper display resolution to boot.

The mostly VT-100 compatible Terminalscope is built around two AVR microcontrollers: an ATmega328P runs full-tilt to generate the video signal and handle serial I/O, while an ATtiny45 handles keyboard input to avoid interrupting the ’328’s duties. Rather than vector trace each character, a raster-scanning approach is used: the beam follows a fixed X/Y path (like a television), while modulating the Z input (beam intensity) to form an image. The device can be connected to a PC via serial port or USB-to-TTY adapter, or directly to another microcontroller to debug serial output.

We recently showed an oscilloscope being used as a multichannel digital logic display. The Terminalscope provides yet another use for this essential bench tool and could nicely round out a “poor man’s” testing setup. The schematic and full source code are available for download.

Add Pause Button To The Atari 2600

February 23, 2010 by Mike Szczys 21 Comments

We’re sure that if there had been a pause button on the Atari 2600 people would never have moved on to next-generation systems. Now you can dig the gaming relic out of the closet and pause your Atari games for some good old om nom nom.This hack is from the same person who pulled off the Atari 2600 jukebox. By reverse engineering the signals used on the Onyx Jr., which has a pause button, the halt method became clear.

The problem is that the Onyx Jr. uses a different processor than the 2600. A different processor means a different pin-out, and now the clock signal needed to synchronize the pause cycle was missing. But eureka, an abstract source was found. The ready signal from another chip can be used to judge the state of the processor. The small PCB above now interfaces with the Atari 2600 in order to patch in the pause circuit.

[Thanks again Yuppicide, keep ’em coming!]

Looping Foot Pedal

February 23, 2010 by Mike Szczys 23 Comments

This guitar pedal can record, playback, and modify samples. [Colin Merkel], also know for his work on electronic door locks, built this to replicate some guitar effects he heard in recordings. By tapping the button at the bottom with your foot the device begins recording. Another tap stops the recording and starts the loop. That’s where the rest of the controls take over, with settings to adjust the speed of playback, volume, and the type of playback looping. The video after the break gives a great demonstration of these features.

[Colin] built this around a PIC 18F877A with a 256k RAM chip to store the sample. There’s a bunch of other components that go into this and we’re dumbfounded that he built it on protoboard. This would be a multi-breadboard prototype for us and we wouldn’t think twice about laying out and etching our own PCB. He admits that the point-to-point soldering stretched his skills to the limit but he doesn’t say how many hours it took to get the circuit up and running. This is a great addition to the cool guitar pedals we’ve seen here.

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DIY Aluminum Heat Sink Casting

February 23, 2010 by Mike Szczys 43 Comments

[Peter Wirasnik] has been casting his own aluminum heat sinks. He’s working on capturing the heat from a car’s exhaust system and turning it into electricity, kind of like the candle generator. In the photo above a standard heat sink is bolted to one side of a Peltier cooler with [Peter’s] own casting on the bottom. That casting will connect to the exhaust pipe and transfer heat to the Peltier while the other heat sink keeps the opposite side relatively cool. What results is a voltage between 600mV and 1V.

We’re not quite sure what the end product will be but the casting process is fascinating. He carves the shape of the piece he wants to cast from Styrofoam and embeds it in a box of sand. He then melts salvaged aluminum in a cast iron frying pan using what looks like a propane torch. Once molten, he pours the aluminum into the mold and it burns away the Styrofoam as it fills the void. A little cleanup and he’s got the heat conductive mounting bracket he was after.